Fix #2721 and cleanup/refactor node registration request (#2789)

- Fix serialization/deserialization of List<DesiredCapabilities>
for GridNodeCofiguration
- Change the format of node config files for Selenium V3 - There
is no need to have the redundant configuration { ... } section.
- Change the message in RegistrationRequest such that it does not
contain dupicative information in separate json objects ..
"id" and "capabilities" are part of "configuration" in Selenium V3
- Cleanup the api for RegistraionRequest -- will break compilation for
people moving from 2.x -- removed the ability to change the
GridNodeConfiguration reference via the RegistrationRequest object and
removed all other setters.
- Add ability to handle booleans in BrowseDesiredCapabilityConverter
- Add GridRole#toString() Override
- Update/Add tests

Author: mach6

java/server/src/org/openqa/grid/common/GridRole.java

@@ -20,24 +20,46 @@
 public enum GridRole {
   NOT_GRID, HUB, NODE;
 
+  private static final String WD_S = "wd";
+  private static final String WEBDRIVER_S = "webdriver";
+  private static final String NODE_S = "node";
+  private static final String HUB_S = "hub";
+  private static final String STANDALONE_S = "standalone";
+
   public static GridRole get(String role) {
     if (role == null || role.equals("")) {
       return NOT_GRID;
     }
     switch (role) {
-      case "wd":
-      case "webdriver":
-      case "node":
+      case WD_S:
+      case WEBDRIVER_S:
+      case NODE_S:
         return NODE;
 
-      case "hub":
+      case HUB_S:
         return HUB;
 
-      case "standalone":
+      case STANDALONE_S:
         return NOT_GRID;
 
       default:
         return null;
     }
   }
+
+  public String toString() {
+    switch (this) {
+      case NODE:
+        return NODE_S;
+
+      case HUB:
+        return HUB_S;
+
+      case NOT_GRID:
+        return STANDALONE_S;
+
+      default:
+        throw new IllegalStateException("Unrecognized GridRole");
+    }
+  }
 }